1. Field
Pumps and compressors.
2. Background
Embodiments of prior art two-phase (liquid/vapor) systems use a pump or a compressor to force either liquid or vapor through the system to, for example, cool various heat sources in the system. A two-phase system generally contains 10%-20% liquid and 80%-90% vapor within the interior of the system.
Typically, prior art embodiments orient the pump or compressor in a manner that will discourage the accumulation of vapor in a liquid pump after the system shuts down. Likewise, systems using a vapor compressor will orient the compressor in a manner that will discourage the accumulation of liquid in the compressor after the system shuts down.
In embodiments using a liquid pump, the pump pumps liquid through the system and is generally oriented at the lowest gravitational point in the system. The reason for this orientation is, when the system shuts down, gravity causes the heavier liquid to accumulate at the lowest point in the system while the lighter gases “bubble” to the highest point in the system. Having liquid accumulate at the lowest point in the system, and thus where the pump is located, is desirable since liquid pumps do not pump vapor very well. In fact, liquid pumps that pump vapor generally malfunction and/or break, and thus shorten the lifetime of the pump.
As a general matter, a liquid pump used in a two-phase system is more likely to encounter a situation where vapor accumulates inside it after shut down rather than during normal operation of the pump since the pump continually pushes liquid through the system. Therefore, the pump's orientation, and thus the risk of having to pump vapor, during operation is generally not a problem. However, when the pump shuts down, the chance the pump will accumulate vapor inside of it increases the farther the pump is away from the lowest gravitational point. Thus, pumps are generally oriented where gravity will encourage liquid to accumulate in the pump and encourage vapor to “bubble” away from the pump (i.e. the lowest gravitational point) after shut down.
Vapor compressor orientation is based upon similar principles as liquid pumps. However, the orientation is the exact opposite. With compressors, it is desirable for the compressor to be oriented at the gravitationally highest point of the system since compressors do not work very well when compressing liquids. Thus, with a high point orientation, vapor will “bubble” toward the high point, and thus accumulate in the compressor after shut down, while any liquid will flow toward the lowest gravitational point in the system.
Problems occur when a system requires a pump to be oriented somewhere other than the gravitational low point of the system or requires a compressor be oriented somewhere other than the gravitational high point of the system. When such a situation occurs, the pump or compressor may not deliver the desired performance and/or may not be capable of operating at all.